As I read the first post, I already had decided in my head that these curse cards were already far too strong in their current state. Give me a break, a curse card that gives -VP equal to the amount of cards in your deck? That's insanity.
Thankfully, you already decided that you were going to water down the Curses somewhat. Firstly, let me say that these Curse givers need to be incredibly expensive to buy, and must give you a marginal to no effect in order to be used, since the Curse attack is incredibly strong. This is the way it has to be. If there is good trashing, it won't be worth going for at all until the late game, where the deficit in points might be a deciding factor. If there is bad trashing, then of course it's still not great to go for until late game, as the curses can be trashed, and there's almost no benefit to you. However, if there is NO trashing, then these cards instantly become very strong and must be pursued, unless there is some crazy quick rush strategy.
Now that this is out of the way, I will now look at the Scaled Curses one at a time, and try and determine a fair amount of Curse effect.
1. Action Curse
The Action Curse should give you -1 VP for every 4/5 Action cards in your deck. This won't be incredible in a BM heavy deck, but you won't want the Curser giving these out in that game anyways, which makes this card a stronger Curse in engines, except of course the all cards option.
The Action Curse Attack should give you no benefit at all, or at most +1 Card or something heinous. The reason for this is twofold: Firstly, this card is great for attacking opponents in big engine games, where a lot of Action cards are going to be readily available. Secondly, this card should be able to also give out either 2 Ruins, or an Action Curse. That's an insane attack. Probably worth $7 or $6, but I'd have to test this.
2. Victory Curse
The Victory Curse can probably be -1 VP for every 3 Victory cards, and such an attack on the board will probably mitigate Duchy Dancing (because Duchies get worth less and less with each purchase) and Silk Road strategies.
The Victory Curse Curser can be a little stronger, with a +$1 bonus, but should probably be worth about $5 or $6.
3. Treasure Curse
You start with 7 Coppers in your deck, so this must be considered automatically. I would say that this Curse should give a -1 VP for every 4 or 5 Treasures. It's not a strong Scaling Curse, and it probably won't ever get above -2 VP (unless Mountebank happens...)
The Treasure Curser could be like Mountebank and hand out Coppers, but this is so ridiculous and OP that it cannot be like this. I think it should give your opponent a Silver, give him a Gold, or give him nothing at all. Also, it could be some special Copper card that puts itself back into a pile like Spoils when used, but it's a useless copper card essentially. Just a temporary junking attack idea I've had in my head for awhile. It should cost $5, it should not be giving out +$2 like Mountebank unless it gives out nothing with that Curse.
4. Card Curse
This card gets stronger and stronger as the game goes on, and if there's no trashing, losing this split is practically an automatic loss. I do not feel comfortable even having such a card in the game. It will either be too strong or too weak. I do not recommend this card at all.
Those are my initial thoughts.